Vulcanizable compounds and vulcanized products derived therefrom



Patented Dec. 6, 193i UNITED STATES PATENT OFFICE JosEPiI C. PATRICK AND NATHAN M. MNOKIN, or xANsAs CITY, MISSOURI vunCANIz BLE COMPOUNDS AND vULCANrzEn IPROIDUCTS DERIVED Tnnnnrnom No Drawing. Application filed May 28, 1928, Serial No. 281,351. Renewed October 3,1932.

This invention relates to vulcanizable compounds and vulcanized products derived I therefrom.

In application Serial No. 239,808, filed December 13, 1927, by one of us, there is described a new plastic derived from the interaction of halogen additive compounds of olefins with soluble polysu'lfides, especially those of the alkali;metals, alkaline earth metals and ammonia, which may conveniently be termed alkaline polysulfides. These plastics may be conveniently designated olefin polysulfide plastics, since in their production, the halogen is eliminated. The mechanical properties of such plastics can be controlled to a considerable degree by regulation of the sulfur content of the polysulfide used in their preparation. For example, ethylene halogen additive compounds react with polysulfide solutions with a sulfur content corresponding approximately to the formulae Gas, and Na s to give a soft, pliable and elastic plastic, somewhat resembling soft vulcanized rubber in appearance, while lower polysulfides corresponding in sulfur content to N a S or Na s, or a mixture thereof give hard plastics which resemblevulcanite in appearance and mechanical properties. These plastics are characterized by a high sulfur content. The soft plastic derived from ethylene di-chloride may contain between 74 and 85% of'sulfur while the hard plastic has a somewhat lower sulfur content. The hard plastic melts around 100 to 120 C. while the softer plastic softens above 140 C. but does not become as fluid as the molten hard plastic.

Both the hard plastic and the soft plastic as well as plastics of intermediate classification are employed according to the present invention by'bemg incorporated with unvulcanized rubber together with sulfur and, if desired, with fillers, pigments and other additions to yield vulcanizable compositions which can be readily vulcanized to give prod 4 ucts closely resembling soft vulcanized rubiberin mechanical properties and general uti ity. In general, it is preferred to employ the soft plastics because of their higher sulfurcontent, cheapness and the superior proper-- tiesofithe resulting'produ'cts.

mill at about 80 C.

. The relative proportions of plastic and sulfur can be varied over very wide limits. For example, we have found that valuable prod? ucts may be obtained by incorporating with plastic, rubber to the amount of 3% thereof, together with a suitable amount of sulfur and vulcanizing. In general, however, it is preferred to employ larger percentages of rub-' ber.

The amountof sulfur which the composition may contain may also vary over very wide limits. A suitable amount of sulfur is that sufiicient for the vulcanization of the rubber content, for example, about 5% more or less of the rubber. It is found, however, that very considerable quantities of elementalsulfur', for example, equal in quantity to the rubber or greater, may be added to the com pound Without adversely affecting the properties of the vulcanized product. The employment of such-excess of sulfur haslittle or no effect upon the hardness of the vulcanized product which resembles soft vulcanized rubber in mechanical properties.

Small quantities of various vulcanizing accelerators, such as diphenyl guanidine,

hexamethylenetetramine, aldehydeammonia,

aniline, thiocarbanilide and thermlo F, may

be added to the composition before vulcanization. Ordinarily theaddition of such accelerators is unnecessary'since the plastic appears to exert a considerable accelerating effect upon the vulcanization of the rubber content. Othersubstances which may be added comprise lead oxide, zinc oxide, magnesium carbonate, magnesium'oxide, calcium oxide, calcium carbonate, pigments, carbon black, glue and other additions employed in rubber compounding.

In preparing the unvulcanized-composition, the plastic,-sulfur, unvulcanized rubber and additions, if any, are incorporated in a ture is below the melting or softening'point of the plastic, the materials become thoroughly mixed without difficulty. The re su-lting compound is rubbery to the touch and can be readily molded and formed into desired shapes, belng softened by heat if'neo- Although the temperaanalogous to the vulcanization of rubber. The invention; will be more completely understood from the followin exam les. The lastic employed therein is erived rom ethy ene.

Ezvamplel Per cent Hard plastic (68.6% sulfur) 28. 5 Coagulated rubber latex 28. 5 Sulfur -Q. 25. 6 Zinc oxide 17.4 These ingredients were milled as described above and on cooling gave agrayish white substance of board-like hardness. When vulcanized for 7 0 minutes at 275 F. it yielded a product free from bloom and having the same appearance as'inner tube rubber. The elasticity was extremely good but the strength was somewhat poorer than the similar product derived from the soft higher sulfur plastic. The sulfur content of the product is 45.1%.

Example [I Per cent Soft plastic (83.1% sulfur) 35. 6 Coagulated rubber latex 35. 6 Sulfur 14.3 Zinc oxide z 14. 5 The product of vulcanization under the condltions stated in Example I gave a similar result except that the product had a much greater tensile strength and a low permanent set. The sulfur content of the product is 43.9%.

' E mample III Per cent Soft plastic (84.0% sulfur) 69.3 Smoked sheet rubber 6.9 Lead oxide 6.9 Sulfur 6.9 Coal tar pitch 6.9 Carbon black 2.8 Thiocarbanilide 0.3

The composition is vulcanized at 270 F. for

- 105 minutes. While its properties such as the vulcanized product possesses considerable .The sulfur content of the product is about I Ewample I V Percent Soft plastic "-24.5 Smoked sheet rubber 36.7 Sulfur 18.4 Zinc oxide 12.3 Zinc stearate 2.5 Hard wood pitch 2.5 'Carbon black 2.5 Pine tar 0.3 ThermloF 0.3

tensile strength and wide limits of elasticity.

The composition'is readily vulcanized'under' conditions similar to those set forth in previous examples.

The composition is vulcanized'for minutes at 30 lbs. of steam.

With the exception of the product of Example III, the products are strong elastic materials resembling with respect to strength, elastic properties and outward appearance, soft vulcanized rubber of superior quality. Generally with increase of rubber content the tensile strength increases and permanent set becomes lower. These compositions possess remarkable resistance to oxidation and sun cracking. The resistance to oxidation decreases somewhat with increasing rubber content.

Notwithstanding the high amounts of free sulfur which may be contained in the vulcanized products, they do not exhibit bloom which occurs in vulcanized rubber which con tains excessive amounts of free sulfur.

By the term unvulcanized rubber, we intend to includenot only new or raw rubber but also reclaimed rubber. In general the products containing reclaimed rubber are less satisfactory than those produced by the use of raw unvulcanized rubber.

Although the present invention has been described in connection with the details of specific examples thereof, it is not intended that such details shall be regarded as limitations upon the scope of the invention except in so far as included in the accompanying claims. I

We claim:

1. A vul-canizable composition comprising high sulfur plastic of the type of additive olysulfides of olefines of the general formula. H unvulcanized rubber, and sulfur. 2. A vulcanizable composition comprising high sulfur plastic of the type of additive polysulfides of olefines of the general formula C 2na unvulcanized rubber, and sulfur in amount at least sufiicient for the vulcanization of said rubber.

3. A vulcanizable composition comprising high sulfur plastic of the type ofadditive polysulfides of olefines of the general formula C,',H unvulcanized rubber, and sulfur in amount considerably exceedin that necessary for the vulcanization of said rubber.

4. A vulcanizable composition comprising high sulfur plastic of the t polysulfides of olefines of t e general formula C H, unvulcanized rubber in substane of additive I tial quantities relative to the amount of plastic and sulfur.

5. A vulcanizable composition comprising hi h sulfur plastic of the type of additive po ysulfides of olefines of the general formula C H unvulcanized rubber in substantial quantities relative to the amount of plastic and sulfur in amount at least sufiicient for the vulcanization of said rubber.

6. 'A vulcanizable composition comprisin high sulfur plastic of the type ofadditive pfiysulfides of olefines of the general formula C H unvulcanized rubber in substantial quantities relative to the amount of plastic and sulfur in amount considerably exceeding that necessary for'the vulcanization of said rubber.

7. A vulcanizable composition comprising high sulfur plastic of the type of additive vpolysulfides of olefines of the general formula (l H unvulcanized rubber, and sulfur, in substantially equal quantities. I

8." A vulcanizable composltion comprlslng A high sulfur soft plastic of the type of additive mula C Hzn, unvulcanized rubber, agid sulfur.

9. A vulcanizable composition comprising high sulfur soft plastic of the type of additive polysulfides of olefines of the general formula G H unvulcanized rubber, and sulfur, in amount at least suflicient for the vulcanization of said rubber.

10. A vulcanizable composition com rising high sulfur soft lastic of the type 0 additive pol sulfides of olefines of the general formula CZH unvulcanized rubber, and sulfur in amount considerably exceedin that necessary for the vulcanization of sai rubher.

11. A vulcanizable composition com rising high sulfur soft plastic of the type 0 ad'- ditive polysulfides of olefines of the general formula C I-L unvulcanized rubber in substantial quantities relative to the amount of plastic and sulfur.

12'. A vulcanizable composition com risi ing high sulfur soft plastic of the t pe 0 additive p'ol sulfides of olefines of t e general formula ,H unvulcanized rubber 1n substantlal quantities relative to the amount of plastic-and sulfur in amount at least suflicient for the vulcanization of said rubber.

13. A vulcanizable composition comprisin high sulfur soft plastic of the t of additive polysulfides of olefines of t eeneral formula CnH unvulcanized rubber in substantial quantities. relative to the amount of plastic and sulfur in amount considerably exceedin that necessary for the vulcanizatiofl of sai rubber.

14. Avulcanizablecomposition'com rising high sulfur soft plastic of the ty 0 add;- tive polysulfides of olefines of fife general formula C H unvulcanized rubber, and sulfur, in substantially equal quantities.

15. A vulcanized com osition of matter,

comprising high sulfur p astic of the type of additive polysulfides of olefines of the gen eral formula G H unvulcanized rubber in substantial quantities relative to the amount of glastic, and sulfur, vulcanized to ether.

1 A vulcanized composition 0 matter comprising high sulfur plastic of the type of additive polysulfides of olefines of. the eneral I formula O H unvulcanized rub er in substantial quantities relative to the amount of plastic and sulfur in amount considerably exceeding that necessary for the vulcanization of said rubber, vulcanized together.

18. As an article of manufacture, a vulcanized material strongly resembling soft vulcanized rubber in mechanical pro erties containing a plastic of the type of a ditive polysulfides of olefines of the general forpolysulfides of olefines of the general formllla 'cnHzn, rubber nd Sulfur, the total proportion of sulfur uncombined and .combined with the rubber and in the olefine polysulfide plastic being not substantially less than 50 0. v

' In testimony whereof we have hereunto set our hands and seals this 10th day of May,

JOSEPH o. PATRICK.

NATHAN M. momma ile 

